1. Field of the Invention
This invention relates to an internal combustion engine which is provided with a sound-insulating enclosure, which defines a sealed passage, particularly for the exhaust manifold, wherein the sealing means associated with the passage comprise a sealing ring, which consists of a rubber-elastic material and is disposed between an inner flanged ring that is secured to the engine block and an outer flanged ring that is secured to the enclosure.
2. Description of the Prior Art
An effective sound insulation of such engine cannot be ensured unless the enclosure encloses the engine as completely as possible and the enclosure has no unsealed passages. Besides, the enclosure must be connected to the engine block by supporting means which are highly elastic in order to provide an insulation against structure-borne sound. Those supporting means and the sealing means which are associated with passages extending through the enclosure must be able to take up and compensate the sometimes considerable relative movements which occur during operation. The known sealing means associated with such passages comprise an elastomeric sealing ring which is disposed between and vulcanization-bonded to two metallic flanged rings and may be designed in such a manner that they will sufficiently seal those passages which contain engine parts which will assume only moderate temperatures, such as the air intake duct, lines for coolant and fuel, and the like, because those parts will not adversely affect the temperature-susceptible sealing material. On the other hand, the sealing of passages for hot parts of the engine, particularly for the exhaust manifold, has previously given rise to great difficulties because the seal has been subjected to very high temperatures and in that case even expensive structures provided with special cooling means have not produced the desired result. Heat-resisting metal bellows seals have not been satisfactory too because they do not sufficiently insulate against structure-born sound.
The sealing of a passage will be particularly difficult if the passage is covered by a cap which is required for sound insulation and which adjoins the enclosure and covers the exhaust manifold. In that case, a sound insulation is required between the enclosure and the cap and an oil-resisting seal is required to prevent an ingress of oil or the like into the hot cap. EP No. 0 062 031 B1 discloses for the mounting of such cap a loose assembly comprising an elastic seal and heat-resisting laminated flat seals, which insulate against structure-borne sound. But in spite of the high expenditure involved in the manufacturing and installation of such cap mounting the latter is not fully satisfactory.